Re: postgres table have a large number of relpages and occupied a big memory size

On 9 Srpen 2011, 9:18, Vivekkumar Pandey wrote:
> I have seen that autovacuum takes long time to process .
> please give me the reason ......

What do you mean by "takes long time to process"? How do you measure it?

Autovacuum is meant as a background process, and it should run on
background and not influence the performance significantly. In some cases
the default settings is not aggressive enough, so the database grows.

In that case you probably need to
- lower autovacuum_vacuum_threshold
- lower autovacuum_vacuum_scale_factor
- lower autovacuum_vacuum_cost_delay
- increase autovacuum_vacuum_cost_limit

But I'm not sure this is the case. And this does not release the space,
it's still occupied by the database (just ready to be reused by new data).

If you really want to compact the database, you may run VACUUM FULL. But
that may be very intensive process, locks tables etc.

Tomas